With development of semiconductor technologies, and standardization of wireless local area networks (WLAN, Wireless Local Area Networks) by 802.11 standards, costs of WLAN technologies are greatly reduced, and the WLAN technologies are also applied increasingly widely. At present, versions of the 802.11 standards already evolve from 802.11a/b into 802.11g, 802.11n, and 802.11ac, and interoperability between products of the 802.11 versions of needs to be authenticated through rigorous testing.
To ensure backward-compatibility and interoperability between products of different versions of the 802.11 standards, starting from 802.11n, a mixed format (MF, Mixed Format) preamble (which is referred to as preamble for short below) is defined. A legacy part of the preamble includes a legacy field that is the same as that of 802.11a.
FIG. 1 shows a structure of an existing preamble. As shown in FIG. 1, a legacy part of the preamble includes three fields, that is: a legacy short training field (L-STF, Legacy-Short Training Field), a legacy long training field (L-LTF, Legacy-Long Training Field) field, and a legacy signal (L-SIG, Legacy-Signal) field, where the L-STF field is used to detect start of frame, set automatic gain control (AGC, Auto Gain Control), estimate an initial frequency offset, and synchronize an initial time; the L-LTF is used to more precisely estimate a frequency offset and synchronize a time, and is also used to generate channel estimation for receiving and balancing the L-SIG; and the L-SIG field is mainly used to carry data rate information and data length information, so that a receive end device can determine a length of data according to the data rate information and the data length information, where the data and the preamble are carried in a same frame, so as to determine an appropriate time to remain idle.
However, in a situation of a poor transmission condition (for example, a low signal-to-noise ratio), a probability that a false positive error occurs in bits carried in the L-SIG field increases, resulting in that the receive end cannot acquire correct length information or the like, and possibly cannot receive or send a valid frame within a period of time, which greatly reduces a throughput rate of a system, and severely affects data transmission performance and user experience.
Therefore, it is intended to provide a technology that can improve a throughput rate of a system, and improve data transmission performance and user experience.